Computer Aided Design (CAD) works exactly like modelling with clay you have to have the skill set to be able to interpret 2d drawings into the 3d world, with CAD you are just doing it virtually, when the customer is happy you can have the piece printed.
The advantages of CAD include the ability to producing very accurate designs. Drawings can be created in 2D or 3D and rotated and other computer programmes can be linked to the design software. CAD is a type of software that many industries rely on to create drafts and models.
Product development time, product quality, and productivity all improve when using CAD, which translate to reduced manufacturing and product costs.
Before CAD, designers were forced to draw everything by hand. If they wanted to alter the design, they would have to draw the entire thing again. CAD software allows designers to visualise their designs and test them against real-world variables. Should something need to be changed, they can easily alter the same file.